Okey then. How fast would a object be traveling in constantly accelerating at the speed UA suggests after 1 year? I'm very aware that a object with mass can reach the speed of light. But requires explinentianly more energy the closer you reach the speed of light. Where does this constantly increasing source of energy come from?
I thought you were good at maths?
You need to consider special relativity ...
The equation to calculate your speed is an asymptote. You never reach light speed a constant acceleration of 9.81m/s as counter intuitive as that may sound.
The relevant equation is v/c = tanh (at/c). Since tanh(at/c) is always less than 1, you can never reach the speed of light.
According to the theory of special relativity, earth accelerating at one standard gravity (9.80665 m/sē) will have the speeds shown below.
T (days), v/c
10, 0.028255
20, 0.056465
30, 0.084586
40, 0.112572
50, 0.140380
60, 0.167969
70, 0.195298
80, 0.222326
90, 0.249017
100, 0.275335
110, 0.301246
120, 0.326721
130, 0.351729
140, 0.376245
150, 0.400245
160, 0.423708
170, 0.446617
180, 0.468954
190, 0.490707
200, 0.511865
210, 0.532420
220, 0.552366
230, 0.571698
240, 0.590416
250, 0.608520
260, 0.626012
270, 0.642895
280, 0.659176
290, 0.674862
300, 0.689961
310, 0.704482
320, 0.718437
330, 0.731836
340, 0.744692
350, 0.757019
360, 0.768829
1 year, 0.774818
400, 0.811193
500, 0.888158
600, 0.934877
700, 0.962469
2 years, 0.968315
800, 0.978500
900, 0.987726
1000, 0.993007
3 years, 0.995924
4 years, 0.999482
5 years, 0.999934
So it will never get to the speed of light. It will tend towards light speed, but never ever ever get there.
So FET is sound in this respect too.